Quantum Immortality: Could We Live Forever in Multiple Universes?

The concept of Quantum Immortality finds its origins in Hugh Everett’s Many-Worlds Theory, offering a radical perspective on the nature of life and death.

Everett, the man behind quantum immortality, famously suggested: “If something can happen, it will happen.” And that’s where our starting point is.

You may remember Schrödinger’s Cat thought experiment.

(In this thought experiment, a cat is considered both alive and dead inside a closed box because its state is unobserved. When observed, the cat’s status becomes definite—either alive or dead. This highlights the uncertainty of quantum particles and the influence of observation on outcomes.)

Until we observe it, we don’t know if the cat is dead or alive, so we assume both are true. Quantum physicists, led by Niels Bohr, argue that the moment someone observes the cat, all possibilities collapse into one. If the cat is alive, then the possibility of it being dead is eliminated forever.

However, another interpretation stemming from quantum physics is the Many-Worlds Theory.

According to this theory, when we open the box and find the cat alive, we’re also opening the door to another universe—one where the cat is dead. In this parallel universe, a copy of us opens the box and finds the cat deceased. Essentially, you’re opening the box twice: once in this world, once in another, different universe, with different versions of ourselves.

The catch? You will never be aware of your other self. It’s as if you’re on two separate paths that diverge forever. When you turn right, you also turn left—but in a different universe.

In fact, you can test this concept yourself—quite simply.

Imagine taking the place of Schrödinger’s Cat.

Let’s tweak the experiment by increasing the number of atoms in a radioactive substance, making survival extremely unlikely. Let’s say there’s a 50% chance at least one of 100 atoms will decay within a second, making survival nearly impossible for our physicist.

The idea here is that, if multiple universes exist, even if survival odds are slim, they aren’t zero. Logic suggests that, at least in one universe, the physicist will survive.

In that universe, our physicist might emerge unscathed from the box, to the astonishment of everyone in the lab. He’d likely be celebrated worldwide, dubbed “the immortal man” or “the miracle man” (assuming the story doesn’t get buried under other headlines).

But something would be overlooked: according to the Many-Worlds Theory, our physicist would have already died countless times across countless other universes. In several realities, he might even make it onto bizarre lists for “strangest deaths” alongside some notorious names.

Without ever knowing he’s a hero in another universe.